Alzheimer's through blood: scientists have found an alarming trace in transfusions

British neurologists published a review in The Lancet a review from which follows: Alzheimer's disease may not always occur on its own — its protein “seeds” can enter the body through a blood transfusion. There is little evidence yet, but researchers believe that it is no longer possible to turn a blind eye to this.

A disease that not only “starts on its own”

Alzheimer's has been considered a sporadic disease for decades — that is, one that develops on its own under the influence of age, genetics and lifestyle, reminds xrust. But in recent years, doctors have accumulated enough data to doubt: perhaps some cases are triggered from the outside, almost like an infection. We are not talking about a virus in the usual sense, but about the amyloid-beta protein — the same one that forms the characteristic plaques in the brain in Alzheimer's. The hypothesis is that this protein is capable of behaving as an infectious agent: when entering a healthy body, it can “persuad” normal proteins to fold into the same harmful form.

This is exactly what a new review in the journal The Lancet is devoted to, prepared by the team of neurologist John Collinge from University College London (UCL). Scientists have pieced together scattered observations from the last ten years and tried to answer a specific question: can amyloid-beta be transmitted through donor blood.

What was already known before

The first alarm bells sounded back in 2015, when a study first showed that amyloid pathology could, in principle, be transmitted between people during medical procedures. A year later, new work confirmed these suspicions with additional data. And in 2018, it was suggested that even poorly processed surgical instruments can act as carriers — through a mechanism similar to the spread of prions, infectious protein particles that provoke Creutzfeldt-Jakob disease and other deadly brain pathologies.

But the topic of blood transfusions was made to be taken truly seriously by a large-scale study in 2023, conducted on data from Denmark and Sweden — over a million people. It turned out that people who received blood from donors who subsequently developed intracerebral hemorrhages were themselves more likely to experience repeated brain hemorrhages years after the transfusion.

Why does this indicate Alzheimer's

Spontaneous cerebral hemorrhages are a characteristic symptom of cerebral amyloid angiopathy (CAA). This is a separate disease from Alzheimer's, but it is associated with the same amyloid-beta, which is deposited in the walls of brain vessels, and not in tissues, as in classic dementia. According to Collinge’s team, the most likely explanation for the Danish-Swedish data is that early amyloid-beta “seeds” that had not yet formed into the disease were already present in the donors’ blood, which were transferred to recipients along with the transfusion.

The authors of the review themselves urge not to rush to conclusions: there is no rigorous evidence of such a mechanism yet, and they directly warn colleagues not to overestimate the significance of the find. At the same time, the text of the article states that the risk of transmitting amyloid pathology through donated blood is a “reasonable cause for concern,” although data to assess the scale of the problem or to develop protective technologies is still critically lacking.

What scientists propose to do

class=»notranslate»>__GTAG5__ The first step, according to the authors, is large epidemiological studies modeled on the Scandinavian work to understand whether something other than the blood itself is actually transmitted through blood. Next comes increased monitoring of patients at risk, primarily those who require transfusions regularly. And finally, the development of a biomarker system that would make it possible to identify donors potentially carrying amyloid pathology before donating blood.

A lesson that Britain has already learned

The authors of the review have a very specific argument in favor of not waiting for 100% clarity — this is the history of contamination of donated blood in the UK. An investigation into contaminated blood, the results of which were published in 2024, found that from the 1970s to the 1990s, more than 30,000 patients in the British National Health Service received contaminated blood products and donations. The incident has been described as the worst medical disaster in the history of the British health system. Collinge explicitly cites this case as a cautionary tale: Waiting for absolute proof of risk before taking patient safety measures is a strategy that has already proved costly.

It is worth recalling that Russia experienced similar stories of infection through blood in the nineties, when the control of donor material for hepatitis and HIV was just being built, so the topic of transfusion safety sounds familiar not only to the British audience.

Outside opinion: the alarm is premature, but justified

class=»notranslate»>__GTAG5__ External experts who did not participate in the review evaluate it with restraint. Susan Koolhaas, executive director of research and partnerships at Alzheimer's Research UK, said the work highlights an important gap in knowledge. According to her, the authors of the review justify the need for separate studies — it is necessary to establish whether transmission through blood really occurs, who is at increased risk, and whether protective measures are required at all. To date, in her assessment, there is simply not enough evidence to answer these questions, so the topic requires further study.

In other words, the very possibility of transmitting Alzheimer’s through blood transfusion remains at the level of a working hypothesis, supported by indirect data, and not by an established medical fact. But the hypothesis already has enough weight to get onto the pages of one of the most authoritative medical journals in the world — and for the blood transfusion system in different countries to start looking at donors a little more closely.

Sources:
sciencealert.com
ucl.ac.uk
thelancet.com

Xrust Alzheimer's through blood: scientists have found an alarming trace in transfusions